Catalyst and hydrocarbon conversion therewith



United States Patent CATALYST AND HYDROCARBON CONVERSION THEREWITH Edward J. Janoski, Philadelphia, Pa., assignor to Sun gil Company, Philadelphia, Pa., a corporation of New ersey No Drawing. Application December 29, 1954 Serial No. 478,509

Claims. (Cl. 208-120) This invention relates to a catalytic composition effective in catalytic processes for converting hydrocarbons. More particularly, this invention relates to new and improved catalytic compositions, their preparation, and to a process for converting hydrocarbons employing the new catalyst wherein a specific hydrocarbon fraction, boiling above the gasoline range, is converted to gasoline of high octane rating.

The conversion of various petroleum hydrocarbon fractions by processes such as cracking, reforming, hydroforming, and the like, using a variety of catalysts and reaction conditions, has been described. Such heretofore described processes, however, are not suitable for converting the hydrocarbon fraction boiling substantially within the range of from about 375 F. to 500 F. to high octane gasoline in a single stage. Instead of achieving a good yield of high octane gasoline, there is produced gasoline hydrocarbons of relatively low octane rating usually in low yields, the production of normally gaseous hydrocarbons, such as propanes and butanes, is excessive, and the reduction of catalyst activity is rapid. It has heretofore been necessary to employ at least two stages to convert a petroleum hydrocarbon fraction boiling above the gasoline range, especially a fraction boiling within the range of from about 375 F. to 500 F., to high octane gasoline. Such processes usually involve a cracking stage wherein a portion of the hydrocarbons are converted to hydrocarbons boiling in the gasoline range, and a reforming, or hydroforming, stage to upgrade the octane rating of the gasoline. In the upgrading stage, the use of two catalysts in separate reactors with a hydrocarbon separation step between the reactors, or the use of two catalysts in a single reactor, has heretofore commonly been required.

An object of this invention is to provide a new and improved catalytic composition eifective for converting hydrocarbons.

Another object is to provide a process for converting a hydrocarbon fraction boiling within the range of from about 375 F. to 500 F. to high octane gasoline in a single stage and in good yield.

A still further object is to provide a process for the preparation of a new and improved catalyst.

Other objects and their achievement, in accordance with the invention will be apparent from the following specification.

General A new catalytic composition has been discovered which gives improved results in converting hydrocarbons. The new catalytic composition contains ruthenium oxide, manganese oxide, silica and alumina in defined quantities, as hereinafter discussed. It has been found that this new catalytic composition is especially effective in converting relatively high boiling petroleum fractions, e.g. a fraction boiling within the range of from about 375 F. to 500 F., to gasoline hydrocarbons of high octane number, and that the normally gaseous hydrocarbons Patented May 19, 1959 produced in the process are remarkably high in olefinic content, so that such normally gaseous hydrocarbons are especially suitable for subsequent processing in reactions such as polymerization and alkylation.

The reactions involved in the process of the invention are primarily the cracking of the relatively high molecular weight hydrocarbons to hydrocarbons boiling in the gasoline range, and the dehydrogenation of hydrocarbons to produce hydrocarbons of higher octane number, such as the dehydrogenation of naphthenes to produce aromatic hydrocarbons. Hence, the process of the present invention is conveniently designated herein as dehydrocracking. Other reactions, however, are involved and assist in producing the high octane hydrocarbons prepared by the process, such as the isomerization of paraffins to produce more highly branched chain parafiins of relatively high octane number, and cyclization followed by dehydrogenation to produce aromatics from parafiins.

The new catalyst of the invention may be prepared by a variety of means, the general techniques of which are known in the art. However, a new method has been discovered which gives an especially effective catalyst. This new method of preparation is described hereinafter.

It is of primary importance that the limits on the ranges of components of the catalytic composition be observed as hereinafter discussed.

The catalyst As above stated, the catalytic composition of the present invention contains ruthenium oxide, manganese oxide, alumina and silica. It is important that the weight percent, based on the final composition, of each component be within the following ranges: ruthenium oxide=0.05 to 5, manganese oxide=1 to 12, alumina=6 to 20, and silica=63 to 92. The values for ruthenium oxide are herein calculated for Ru O and for manganese oxide are calculated for MnO, but it is realized that these oxides may exist as mixtures with other oxides wherein the metal has a different valency.

When the quantity of ruthenium oxide in the catalytic composition is below 0.05% by weight, a substantial loss of octane rating of the gasoline hydrocarbons is observed, whereas in quantities above 5% by weight, excessive coke formation on the catalyst is observed. When the quantity of magnesium oxide is below 1% by weight, a substantial loss in octane number of the gasoline product is observed, whereas at concentrations above 12% by weight, conversion of higher boiling hydrocarbons to hydrocarbons boiling within the gasoline range is low. If the quantities of alumina or silica are varied from the stated ranges, the conversion of the high molecular weight hydrocarbons to hydrocarbons boiling in the gasoline range is adversely effected. Accordingly, it is of primary importance that the components of the catalytic composition be within the stated ranges.

Preparation of catalyst joint precipitation of alumina and silica from aqueous solutions of their salts, and by washing, drying, and heating the resulting composition.

The remaining components of the catalytic composition may be deposited on the silica-alumina composition by using solutions of soluble compounds of the metals. Impregnation is advantageously performed by using aqueous solutions of water soluble salts of the materials. Impregnation may be with the ruthenium salt followed by the manganese salt, by the manganese salt followed by the ruthenium salt, or simultaneously with the same aqueous solution. However, it is preferred to impregnate silica-alumina with an aqueous solution containing both a ruthenium salt and a manganese salt, and to dry and calcine the impregnated composition to prepare the final composition, since this procedure yields a catalyst of exceptionally high activity in producing gasoline hydrocarbons of high octane rating from higher boiling hydrocarbons. The drying may be accomplished by any convenient means, such as by heating with infrared radiation or by heating at a relatively low temperature, say from about 100 C. to about 200 C. for from about 1 to 20 hours in an oven. The dried composition should be calcined in contact with an oxidizing gas, such as in a stream of air, at a temperature of from about 500 C. to about 750 C. for several hours.

Dehydrocracking The reactions involved in the present process for converting relatively high boiling petroleum hydrocarbons to gasoline hydrocarbons of high octane rating are primarily dehydrogenation and cracking, and hence the overall process is conveniently designated as dehydrocracking. The gasoline product preferably contains only hydrocarbons having a molecular weight lower than the hydrocarbons of the charge stock, and hence includes only the hydrocarbons which have been cracked in the process.

As above stated, the new catalytic composition of the invention is especially suitable for dehydrocracking hydrocarbon fractions boiling in the range of from 375 F. to 500 F. Accordingly, the use of the present catalyst will be described in terms of this preferred embodiment.

Especially suitable charge stocks are straight-run fractions having a naphthene content of at least and preferably above 30%, say from about 30% to 75% by volume. Other fractions such as those obtained from catalytic cracking, and recycle gas oils in general, may be used.

In the process, temperatures Within the range of from 450 C. to 500 C. give good results and with the preferred hydrocarbon charge stock must be observed in order to obtain suitable conversion without excessive coke formation. The pressure is preferably maintained at about atmospheric pressure, but superatmospheric pressure up to about 100 p.s.i.g. can be used if desired. The space velocity must be maintained Within the range of from about 0.5 to 3. It is preferred to employ a space velocity of from 0.8 to 1.5 since within this range there is obtained a high gasoline yield of high octane number. By space velocity, as used herein, is meant the liquid hourly space velocity, which is the liquid volume of hydrocarbons charged per volume of catalyst per hour.

In carrying out the process of the invention, it is preferred to pass the hydrocarbon charge through a bed of catalyst under the above conditions. By such operation the activity of the catalyst is gradually decreased, principally due to the deposition of carbonaceous materials thereon. Periodic regeneration of the catalyst, such as by discontinuing the operation, flushing the cata lyst bed with nitrogen, and burning off the carbonaeous materials by passing an oxygen containing gas, such as air, through the hot catalyst bed, is advantageously employed. Regeneration is generally advantageously employed at intervals of from about 10 minutes to 2 hours, depending upon the particular operation and reaction variables beingused.

Hydrogen is preferably not employed in the process, but a small partial pressure thereof is not deleterious. In some other uses of the present catalyst, however, an atmosphere of hydrogen is advantageous, especially where operation is at superatmospheric pressure, as hereinafter described.

Example In order to illustrate a preferred catalytic composition of the invention and its use in hydrocracking, a catalytic composition. in accordance with the invention, was prepared as follows, in which parts refers to parts by weight:

355 parts of a synthetic silica-alumina cracking catalyst, containing about 13% by weight alumina prepared by coprecipitation and having a cracking activity of about 46, was impregnated with an aqueous solution containing about 1.6 parts of ruthenium trichloride and about 49.3 parts of manganous nitrate. A small amount of excess liquid was drained and the impregnated composition dried for about 16 hours at about C. The dried impregnated composition was then calcined at about 650 C. for 2 hours. The resulting composition constitutes a preferred catalytic composition in accordance with the invention and contained, in parts by weight, 0.22 part ruthenium oxide, 4.28 parts manganese oxide, 12.4 parts alumina and 83.1 parts silica.

In order to illustrate the efiicacy of this new catalytic composition for converting hydrocarbon fractions boiling in the range of from 375 F. to 500 F. to high octane gasoline hydrocarbons, a straight-run hydrocarbon fraction boiling in the range of from about 375 F. to 460 F. was contacted therewith. The following conditions were employed during the contacting: temperature of catalyst=504 0., space velocity=1.00, pressure=atmospheric The catalyst bed was regenerated after operation for 20 minutes by burning carbonaceous materials therefrom with a stream of air as above described. Products were collected over 12 cycles of operation and regeneration.

A yield of gasoline hydrocarbons, i.e., hydrocarbons from pentane to those boiling at 350 F. of 20.7% by volume was obtained. There was also obtained 7.4% by volume of hydrocarbons having 4 carbon atoms and 2.8 weight percent of hydrocarbons having 3 carbon atoms. The bottoms fractions, i.e., hydrocarbons boiling over 350 F. constituted 60% by volume of the charge.

The gasoline fraction had an octane number of 99.3 (ASTM Method D908-53) and an aromatic content of 66% by volume. The hydrocarbons having 3 carbon atoms contained 79% by weight propylene and the hydrocarbons containing 4 carbon atoms contained 57% by weight olefins, principally isobutylene.

If the above example is repeated using, as the catalyst, the silica-alumina composition on which was deposited ruthenium oxide and manganese oxide in the above example, the octane number of the gasoline product is substantially lower and the olefinic content of the normally gaseous hydrocarbons is lower. For example, in a comparable procedure using the silica-alumina composition as the catalyst, the olefinic content of the butane fraction was found to be only 30.5% by Weight, as compared to 57% by weight obtained in the above example.

The foregoing example illustrates a preferred embodiment of the invention, including a preferred catalytic composition and its preferred use in converting a refractory, relatively high boiling hydrocarbon fraction to gasoline having a remarkably high octane number in good yield. The catalyst is also efiective to dehydrocrack other relatively high boiling fractions, such as gas oils boiling from about 400 F. to 750 F. or higher, to gasoline.

When other catalytic compositions within the scope of the present invention are employed, substantially equivaasamao lent results are obtained, and when other operating conditions are employed within the ranges herein described, substantially equivalent results are obtained. The process may also be operated batchwise or as a moving 'bed or fluidized process by maintaining the reaction conditions equivalent to those herein described.

The catalyst of the invention can be used in other reactions involving the conversion of hydrocarbons, such as destructive hydrogenation using elevated pressures in an atmosphere of hydrogen, reforming, and the like, in which catalytic conversion conditions known to be effective in such processes give good results.

The invention claimed is:

1. Process for converting a hydrocarbon fraction boiling above the gasoline range, which comprises contacting said fraction with a catalyst consisting essentially of, in percent by weight, 63 to 92% silica, 6 to 20% alumina, 0.05 to 5% ruthenium oxide and from 1 .to 12% manganese oxide, under catalytic conditions whereby said hydrocarbon fraction is converted to gasoline of high octane rating.

2. Process according to claim 1, wherein said hydrocarbon fraction, boiling above the gasoline range, boils within the range of from 375 F. to 500 F.

3. Process of cracking which comprises contacting a petroleum fraction boiling in the range of from 375 F. to 500 F. with a catalyst consisting essentially of, in

percent by weight, 63 to 92% silica, 6 to 20% alumina, 0.05 to 5% ruthenium oxide and from 1 to 12% manganese oxide at a temperature within the range of from 450 C. to 540 C., a space velocity of from 0.5 to 3 and a pressure of about atmospheric and recovering gasoline of high octane rating from the reaction mixture.

4. A catalyst for use in the conversion of hydrocarbons consisting essentially of, in percent by weight, 63 to 92% silica, 6 to 20% alumina, 0.05 to 5% ruthenium oxide and from 1 to 12% manganese oxide.

5. A catalyst for use in the conversion of hydrocarbons consisting essentially of a synthetic silica-alumina composition impregnated with from 0.05 to 5% by Weight, based on the final composition, of ruthenium oxide, from 1 to 12% by weight, based on the final composition, of manganese oxide, wherein the quantity of silica is from 63 to 92% by Weight, based on the final composition, and the quantity of alumina is from 6 to 20% based on the final composition.

References Cited in the file of this patent UNITED STATES PATENTS 2,437,532 Huffman Mar. 9, 1948 2,463,508 Bates Mar. 8, 1949 2,781,323 Hunter Feb. 12, 1957 

1. PROCESS FOR CONVERTING A HYDROCARBON FRACTION BOILING ABOVE THE GASOLINE RANGE, WHICH COMPRISES CONTACTING SAID FRACTION WITH A CATALYST CONSISTING ESSENTIALLY OF, IN PERCENT BY WEIGHT, 63 TO 92% SILICA, 6 TO 20% ALUMINA, 0.05 TO 5% RUTHENIUM OXIDE AND FROM 1 TO 12% MANGANESE OXIDE, UNDER CATALYTIC CONDITIONS WHEREBY SAID HYDROCARBON FRACTION IS CONVERTED TO GASOLINE OF HIGH OCTANE RATING. 